This invention relates to an apparatus which is capable of machining curved facets onto several blank polygons to be used in raster scanners.
Typically a raster scanner contains a light source, a collimator, pre-polygon optics, a multi-faceted rotating polygon as the scanning element, post-polygon optics and a photosensitive medium. The light source, which can be a laser source, produces a light beam and sends it to the rotating polygon through the collimator and the pre-polygon optics. The collimator collimates the light beam and the pre-polygon optics focuses the light beam in the sagittal or cross-scan plane onto the rotating polygon. The rotating polygon has a plurality of facets.
The facets of the rotating polygon reflect the light beam and also cause the reflected light revolve about an axis near the reflection point of the facet of the rotating polygon. This reflected light beam can be utilized through the post-polygon optics to scan a document at the input end of an imaging system as a raster input scanner or can be used to impinge upon a photosensitive medium, such as a xerographic drum (photoreceptor), in the output mode as a raster output scanner.
Referring to FIG. 1, there is shown a prior art polygon 10. Typically, the facets 12 of a rotating polygon 10 are flat surfaces. However, some raster scanners use a rotating polygon with curved facets.
Referring to FIG. 2, there is shown a top view of a polygon 14 which has curved facets 16. As it is shown, the center C1 of each curved facet is different than the center C of the polygon.
It is an object of this invention to provide an apparatus which is capable of machining curved facets onto several polygons together.